卫星时间尺度的长期模型优化方法的比较

为了降低时间尺度的时间起伏标准偏差，对卫星时间尺度（ＧＰＳ，ＧＬＯＮＡＳＳ）的长期模型优化方法进行了评述，并对时间中心和时间实验室的数据分析进行了检验。结果表明，采用混合模型方法进行修正或控制，卫星时间尺度的长期时间起伏可变为白噪声过程：ＧＰＳ时间尺度的时间起伏标准偏差可下降到１０￣２０ｎｓ，与一天内的短期结果接近，ＧＬＯＮＡＳＳ时间尺度的结果大些，ＧＬＯＮＡＳＳ时间尺度的时间起伏标准偏差的平均改     

多功能高清卫星转播车设计

为满足新闻事件直播报道常态化的需求,南方电视台建设了一辆多功能高清卫星转播车。在功能上不仅满足日常新闻直播连线的应用需求,同时可完成户外小型节目的录制及大型活动的传输任务。从视音频系统、卫星上行系统、车体建设等几个方面介绍该转播车的设计思路、设备、车体选型以及集成实施情况。     

批量卫星流水线自动化测试系统研究

随着世界各国快速进入太空的需求增加,卫星大规模组网应用不断增多。批量生产、并行测试、一箭多星、密集发射已经成为当前卫星技术的发展趋势,对卫星的批量快速测试提出了更高的要求。为了提高卫星测试效率、缩短卫星研制周期、降低卫星测试成本,研究适用于批量卫星流水作业自动化测试系统至关重要。提出了一种适用于批量卫星流水作业自动化测试体系方案,为批量卫星的流水作业自动化测试提供参考。     

Mapping of Landsat Satellite and Gravity Lineaments in West Tennessee

Earthquakes are a common occurrence in west Tennessee. Yet it is difficult to recognize related faults within the alluvial valley because of the unconsolidated sediments. Therefore, a synergetic approach to the analysis of lineament patterns was applied through the use of Landsat satellite and gravity anomaly data. Landsat satellite images were evaluated for lineament identification using different spectral bands, seasons, enhancement, and image interpretation techniques. Gravity trends were delineated on the gravity anomaly map of west Tennessee, and gravity lineaments were identified and mapped. The Landsat and gravity lineaments were quantitatively analyzed and compared by means of two‐dimensional histograms and rose diagrams. The results indicated that the primary direction of both Landsat and gravity lineaments was NE; N36‐63E for Landsat and N27‐72E for gravity. Weaker trends were found in N50‐55W for Landsat and N60‐70W for gravity. The NE trend of the lineaments corresponded to faults and was in accordance with reactivation of the Reelfoot rift near the Mississippi River. These results suggest that deeper features, maybe at the earthquake focal depth, probably extend to the land surface as Landsat detectable lineaments.     

Cropland Measurement Using Thematic Mapper Data and Radiometric Model

To halt erosion and desertification, it is necessary to quantify resources that are affected. Necessary information includes inventory of croplands and desert areas as they change over time. Several studies indicate the value of remote sensor data as input to inventories. In this study, the radiometric modeling of spectral characteristics of soil and vegetation provides the theoretical basis for the remote sensing approach. Use of Landsat Thematic Mapper images allows measurement of croplands in Saudi Arabia, demonstrating the capability of the approach. The inventory techniques and remote sensing approach presented are potentially useful in developing countries.     

人机合作的免疫算法及其在布局设计中的应用

提出一种人机合作的免疫算法（HCCIA）。它将设计者提供的初始人工个体和混沌初始化生成的初始算法个体合并组成初始群体,然后经自适应交叉、变异和免疫选择等算子操作,进化寻优。同时,还适时和适量地将设计者给出的新人工个体加入到算法群体,替换掉其中较差的个体。如此循环,直至达到结束准则。该算法有利于充分发挥人机各自特长,为更好地解决复杂工程设计问题提供了方便。文中以卫星舱布局设计为背景的算例验证了此算法的可行性和有效性。     

环境减灾卫星数据在旱灾预警监测中的应用

环境减灾卫星星座具有宽覆盖和快速重访的能力,尤其适合旱灾等大范围灾害监测的要求。基于权重叠加法的区域旱灾风险评估方法,综合考虑致灾因子、孕灾环境及承灾体等指标,获得的旱灾风险等级分布图可以应用于旱灾风险预警。光谱维-温度旱灾指数产品综合考虑了土壤水分变化、地表蒸散变化、植被绿度变化、植株水分变化4方面内容,可有效应用于旱灾监测中。针对2010年初中国西南地区特大旱灾,利用环境减灾卫星数据采用上述方法开展了旱灾风险评估和监测,并采用民政部国家减灾中心收集的地方政府上报灾情数据对风险评估和监测结果进行了验证,结果表明:监测结果与实报灾情相符,结果具有较高的精度。风险评估和监测结果仍需进一步改进,以满足自然灾害救助应急预案仿真与模拟的精度需求。     

1588v2在电信网应用的标准化进程

文章介绍了1588v2在电信网领域应用的背景、需求和主要标准组织ITU-T的相关工作进展,包括频率同步应用和时间同步应用。通过分析目前1588v2电信应用规范中的热点问题,如影响1588v2频率恢复性能的网络分组延时变化(PDV)指标、1588v2端到端频率传送的应用场景和协议规范,提出1588v2在电信网络部署的可靠性、可管理维护等特点和基本思路,并对未来标准化需要解决的问题进行总结。